1. Field of the Invention
This invention relates to a method of defoaming amine solutions which are used to absorb acidic gases, and more particularly to a method of removing foams which may develop in an amine solution while maintained in continuous contact with such a gas as containing hydrogen sulfide or carbon dioxide.
2. Prior Art
It has been an established practice to bring hydrogen sulfide-containing or carbon dioxide-containing gases into absorptive contact with an aqueous amine solution thereby recovering hydrogen sulfide or carbon dioxide from the respective gases. However, when this contacting operation is continued for a prolonged period of time, the amine solution is liable to undergo foaming or bubbling in the system which would in turn induce increased pressure differential between an absorption unit and a recovery unit, or abnormal liquid level, or entrainment of the amine solution downstream of the unit, or in the worst case, shutdown of the whole plant. To suppress or otherwise eliminate the foams and bubbles, it has been proposed to add some defoaming agents such as higher alcohols, petroleum lubricating oil fractions, esters, silicone oils, and the like.
Such defoaming materials however are not satisfactory for the purpose of defoaming an aqueous amine solution when this is used to treat acidic gases.